THE CASE | A waterfront watchman spies a woman apparently standing at the end of a pier — except she’s actually hanging from fishing line, dead. Arriving on the scene, Kate and Rick note that Lanie looks unusually startled, and for good reason: the corpse is a dead ringer for the M.E., right down to her hair products and a new hip tattoo that Javy (and only Javy) could have known about. The victim, Pam, used to be a street-walker, but shortly after moving to New York City, she told her dad, she landed a sweet gig. The source of her good fortune is a mystery, though, with the only clue being the serial number on her cheek implants. traced to Dr. Kelly Niemann. The plastic surgeon explains to Castle and Beckett that Pam gave her a pic of a “friend” she wanted to look like.

Meanwhile, thanks to a selfie retrieved by Tory from Pam’s phone, the boys stake out a boat at the marina, where they find another strung-up body — that looks like Espo. This victim, Daniel Santos, was a former stripper who — stop me if you’ve heard this before — landed a sweet gig after moving to New York City, from Georgia. Whats more, it’s discovered that Daniel was practicing to talk like Espo, too! Scouting out Santos’ digs, Espo is approached by a spooked neighbor, who says that a town car used to pick Santos up regularly. And on his final such trip, he was deposited at the home of… Dr. Neimann.

But no amount of grilling can cause Niemann to break for Beckett. Instead, the good doc explains away her curious connection to both vics by saying that Daniel, a “purely physical” hook-up, had referred Pam to her. What’s more, Niemann’s alibis for both kills checks out — as proven by a video of Santos leaving her place at night, then getting into a car traced to… waterfront watchman Carl Mathews, who has gone missing after quitting that job. Rick suggests that Carl doesn’t “fit” this crime, that if anything he is working with someone — someone like 3XK aka Jerry Tyson, the killer who dogged them in Season 3. “No evidence, meticulously planned… It’s vintage 3XK,” Rick contends. But no sooner does Kate urge him to not chase ghosts do they discover that all of the 3XK files have been stolen (by Faux Espo), as has all the DNA evidence from those investigations (by Like-Lanie).

The team tracks Carl to a motel — the same place (and room number) where 3XK was put up back in the day — and Rick tackles him. In the interrogation room, Carl claims he is no disciple of Tyson’s but his own man, and as such he’ll ‘fess up to only his own kills — “no more and no less.” He then taunts Caskett with this parting thought: “You think you’ve got this all figured out. But you don’t.” Indeed. A review of Tyson’s prison records show that the visiting doctor during his stint behind bars was none other than Kelly Niemann, and that she left when he did. And now, Niemann is in the wind, her tony office cleaned out save for a pen that, Rick later discovers at the loft, harbors a flash drive….

He plugs it into his laptop, and Vera Lynn’s “We’ll Meet Again,” quite haunting in this context, begins wailing throughout the living space, visibly shaking Beckett to the bone.

THE CASKETT | Before the eeriness of the first murder scene set it, we saw Rick trying to plan his and Kate’s honeymoon, suggesting that the right place and best time will in turn dictate their wedding date. But Kate soon gets wise to his subtle plan to have their honeymoon double as a tour of “Middle Earth” in New Zealand. (“I was hoping for something more romantic and less Hobbit-y.”) But when Kate begins suggesting other destinations, they realize that Rick and his previous mates have already covered much of the globe — save for Albania and Finland. Hmmm.

THE ESPLANIE | Some nice moments for the long-forsaken couple, first as we learn that not only are they still hooking up, but that Lanie, at least, has been a one-man woman. Later, when Espo’s doppelgänger pops up, Lanie frets over who’ll be next. When Javy assures her, “I won’t let anything happen to you,” she worries, “What if something happens to you?” And towards the hour’s end, as they observe the questioning of Carl, Lanie raises a chilling: “How long until we stop thinking about what he’s done, until we stop looking at each other and seeing dead people?” Fair point, that.

THE REVIEW | I know the season-opening D.C. arc had its appeal, but when it comes to a combination of A) ca ompelling (if not entirely realistic) case, B) cast inclusion (Lanie! Gates! MyTory!), C) good Rick/Kate moments and D) solid guest stars (in 24‘s Annie Wersching and Lost‘s William Mapother), you’d be hard-pressed to name a more satisfying Season 6 entry than this. Cinching the deal was how it revived the 3XK storyline (and maybe Tyson himself?) to an extent that is TBD. Is he back? Is Niemann just an obsessed fan? (Is there any way that Carl is Tyson?) Yep, I’m going with Best Episode of the Season. What did you think?